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From:Wynne Crisman Date:March 28 2003 6:06am
Subject:RE: MyISAM rebuilding questions
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Thank you all for the responses,

This information is useful in determining what direction to take in
designing the application's use of the MySQL database.  I am still a bit
unsure how a log based reconsiliation works when the system crashes
(using MyISAM tables).  Does a lengthy reconstruction have to take
place?  Can it be automated (so it occurs when the db is restarted)?
What pitfalls must be avoided? 

Thank you,
Wynne Crisman
patternWare Systems, Inc.

-----Original Message-----
From: Michael Widenius [mailto:monty@stripped] 
Sent: Thursday, March 27, 2003 6:49 AM
To: Wynne Crisman
Cc: mysql@stripped
Subject: MyISAM rebuilding questions


>>>>> "Wynne" == Wynne Crisman <wcrisman@stripped> writes:

Wynne> I am trying to determine what would cause my needing to rebuild 
Wynne> an MyISAM table in MySQL 4.0.x?

You should not have to rebuild any tables just to upgrade to MySQL 4.0
from 3.23.  The MyISAM format has not changed in any way between

Wynne> I also would like to know how I can minimize the time necessary 
Wynne> to get the MyISAM table up and running under MySQL 4.0.x?

zero time for tables without fulltext.
Some time for tables with fulltext indexes.

Wynne> I have read the 
Wynne> document which states that tables with lots of data can be
difficult to
Wynne> rebuild and would be better served using InnoDB, but InnoDB does
Wynne> support fulltext searches.

I don't know of any problems in rebuilding an MyISAM table:

Just do:

OPTIMIZE TABLE table_name;


ALTER TABLE table_name type=myisam;

It's true that MySQL 4.0 has better fulltext capabilities and to get
these activated for a table you need to rebuild the tables that has
fulltext support.

The old tables will however work as before even if you don't rebuild
them (but in this case you will probably not be able to use boolan
search on them until you have rebuilt them).

Note that fulltext rebuilds are MUCH faster in 4.0 so it should not take
long to do the rebuilds.

Wynne> Thank you for any assistence,

Wynne> Wynne Crisman
Wynne> patternWare Systems, Inc.


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MyISAM rebuilding questionsWynne Crisman25 Mar
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